I am building a front mount 5.3L in a S10. The turbo is an On3 78/75 and I want to run E85 non intercooled. Looking to run 12-15#'s. Just wanted to ask some guys with experience if it would be worth opening the ring gaps. I know E85 cools the combustion temps, but running without an intercooler I could see air in temps between 2-300°F. Open to suggestions as to what you have seen work....

 

I would open up the gap if it were me. The stock pistons are not very forgiving if the rings touch. I had a supercharger on pump gas at 12 PSI and had the rings touch. That was a bad day.

 

open them up .if you running factory pistons i would for sure 15 psi is alot with out intercooler

 

Depending on mileage of motor you use the gap may already be opened up

Non-intercooler may not be great idea

 

If the engine has less than 150k, yes open them up, and figure out a way to run an intercooler.

 

Proper ring gap for any specific application is just as important as bearing clearance. Are you a gambling man?

 

is it a good idea? yes. would i bother? no. junkyard sells them everyday. i've been 5 years of 15# or more.

 

Yes but 15lbs from a small turbo isn't same as larger turbo

24-25 psi on stock motor here ........

Ring gaps .028/.028

 

So running the intercooler seeks to be the best bet. What size wastegate are you running with the turbo log setup?